PX625 MR9 Battery Adapter Set Universal for Analog Cameras

Suitable for various cameras, including:

• Canon: Canonet series (QL17, QL19, 28, G-III), F series (F-1, F-1n, FT, FT QL, FTb, FX), TLb, EX, Demi EE17, Dial 35-2, other Canon models
• Nikon: F series (F, F Photomic, FTN), Nikkormat / Nikomat series (FT, FTN), other Nikon models
• Minolta: SR-T series (SR-T 100, 100X, 101, 102, 201, 202, 303, 303b, MC, SC, Super), AL-F, SR series (SR-7, SR 101, SR 505, clip-on CdS meter for the SR-1), Hi-Matic series (7, 7S, 9, 11), other Minolta models
• Olympus: OM-1 series (OM-1, MD, N), 35 series (RC, RD, SP, DC), Pen series (FT, EED), other Olympus models
• Pentax: Spotmatic F, clip-on CdS light meters from Asahi Pentax, other Pentax models
• Rollei: 35 series (35, 35S, 35T, Classic), SL35 series (SL35, SL35M, SL350), XF35 / A26, other Rollei models
• Praktica: MTL3, super TL / super TL 1000, MTL5, LTL / LTL3, other Praktica models
• Leica: M5 (not tested by us, see note below the list), CL / Leitz Minolta CL, Leicaflex (Standard) and SL2 (not tested in the Leicaflex SL with its very tight battery compartment), MR / MR4 light meters, other Leica models
• Yashica: Mat 124 G, Mat 124, Minister-D, Lynx-5000, Lynx 14
• Gossen: Luna-Six 3, Sixtar
• Agfa: Optima 1035, Optima 535, Agfamatic 5008
• Konica: Auto S2
• Honeywell Elmo: Super 108, Super 110
• Also: Revue 400 SE, Argus CR-2, Zenit TTL, Vivitar 35 ES, Chinon CS, Miranda Sensorex, Minox 110 S, Exakta TL-500, Ricoh Singlex TLS

Some cameras take two PX625 cells, for example the Nikon F with Photomic FTn finder, the Konica Autoreflex TC and T4, the Canon EF and the Leicaflex SL2 (light meter and viewfinder illumination). There you need both adapters from the set.

No adapter needed for Konica Autoreflex T, T2, T3, T3N and Konica C35: they take the smaller PX675 from the factory, so you insert the 675 cell directly.

Leica M5: The battery compartment of the M5 is tight. With some PX625 adapters, the screw cap does not close fully there, and we have not yet tried our adapter on an M5 ourselves. If the cap does not screw on easily, do not use force and write to us, we will help you.

Not sure whether the battery fits your camera?
Here you can find a detailed list of cameras that use a PX625.

• Material: Conductive engineering plastic
• Compatibility: Replaces PX625 / MR-9 / PX13
• Battery system: zinc-air type 675 / PR44 (1.4V) only, not for LR44 (alkaline) or SR44 (silver oxide)
• Fit: Universal (side and bottom contacts)
• SKU: 1191

This PX625 adapter, also known as an MR9 adapter, replaces the PX625 mercury battery, which was the standard in many analog cameras from the 70s to the 90s. Since the EU ban on the mercury cell, there has been no common direct replacement. Suitable for, among others, Canon Canonet and F-1, Nikon F, Minolta SR-T, Olympus OM-1, Pentax Spotmatic F, Rollei 35, Praktica MTL and Leica CL. We have since changed the material of the adapter: today's conductive plastic conducts significantly better than the earlier one.

• Inserting correctly: Peel the tab off the cell and place it with the flat side (plus, where the air holes are) on the cross in the bottom of the adapter. The small domed cap (minus) sticks out at the top. Insert the adapter into the camera the same way the old PX625 sat: in almost all cameras, plus, and therefore the cross, faces the battery cover.
• Tightly sealed battery compartment: The zinc-air cell draws its oxygen from the surrounding air and needs a clear air path to do so. Only rarely, for example in splash-proof cameras with a rubber seal in the battery compartment, does too little air get through. The voltage then drops and the light meter cuts out, even though the cell is not yet empty.
• Storage: With the tab on, the cells last several years; the expiry date is printed on the pack. Store them at room temperature.
• Battery check: If your camera has a battery check, such as the B.C. position on the Minolta SR-T, the needle will normally sit within the check zone with a fresh zinc-air cell. Right after inserting the cell, the reading may still be borderline because the voltage is only just rising. Check again after a few minutes.

“How can a plastic adapter provide the correct voltage?”

The voltage comes from the battery, not the adapter. Under the tiny load of a light meter, the Type 675 zinc-air cell delivers around 1.4 V, just slightly more than the 1.35 V your camera is calibrated for. The adapter merely brings the smaller cell to the size of the old PX625 and establishes contact. To make this work with contact from the side as well, it is not made of ordinary plastic but of a conductive material. The current flows through the adapter.

“Zinc-air batteries dry out. They only last a few weeks, right?”

Yes, they dry out, but in a camera more slowly than many people think. Once the protective film is removed, the cell ages even if you are not taking photos: depending on the humidity, it slowly dries out or absorbs water, and it also binds carbon dioxide from the air. In a hearing aid, a 675 cell is usually empty after about 9 to 20 days, because a hearing aid draws many times the current of a light meter. In a camera, it usually lasts 2 to 3 months. Heat and very dry or very humid air shorten this to a few weeks, while in a cool environment it lasts longer. Cameras without an off switch for the light meter, such as the Olympus Pen FT, also use power as long as light falls on the metering cell: put the lens cap on after shooting. Only remove the film when you insert the cell.

“1.4V isn't 1.35V—will my exposure meter give incorrect readings?”

A freshly activated zinc-air cell delivers around 1.4V under the tiny load of a light meter, slightly more than the 1.35V of the old mercury cell. With most cameras, this makes no visible difference: in comparison tests on two Minolta SR-T 101 cameras and a Gossen Luna-Pro, zinc-air cells measured practically the same as 1.35-volt cells. With particularly voltage-sensitive cameras, such as the Olympus OM-1, some photographers report 1/3 to 2/3 of a stop of underexposure. With negative film, this is hardly noticeable. If you shoot slides, run a test roll and, if needed, set the film speed 1/3 to 2/3 of a stop lower.

“Can moisture from the zinc-air battery damage my camera?”

Zinc-air cells use oxygen from the air as the cathode and contain a small amount of electrolyte. The risk mainly concerns empty cells: a deeply discharged zinc-air cell can lose electrolyte through its air holes, and manufacturers warn about this. So remove the cell when it is empty, after about three months at the latest, and also when you will not be using the camera for a longer period.

“Can I insert an LR44 or SR44 instead of the 675?”

No, the adapter is only intended for type 675 zinc-air cells. A 1.5V alkaline battery in a CdS meter calibrated for 1.35V results in underexposure with most cameras. Alkaline voltage also fluctuates significantly over its service life (1.6V when fresh, 1.2V when empty). This makes meter readings unpredictable. Silver oxide (SR44, 1.55V) is more voltage-stable, but still too high. Zinc-air, on the other hand, holds its voltage constant until shortly before the end, like the old mercury cell, and, at around 1.4V, is only slightly above the original.

Want a rechargeable solution?
If you would rather not keep replacing disposable batteries: we developed the PX625 rechargeable battery with USB-C charger (V80H). A rechargeable battery (NiMH) with an operating voltage of 1.25–1.30V, charged via USB-C. Buy once, use for years.

Want to learn more about voltage and exposure metering?
In our FAQ article about batteries and adapters for analogue cameras, we explain all the alternatives in detail, including voltage comparisons and when each solution is the right choice.

How does the adapter compare to a handheld light meter?
Bene from Face of Light Photography measured the set in a Nikon F Photomic FTN and a Minolta SR-101 against a Sekonic L-308X. All readings were at 1/60 s and f/4.5 (ISO 400). His English test report: PX625 Battery Replacement Guide. He received the set from us for free; we did not pay him.